Undifined local variable or method error

Hi all,

Below is my code

h={}
arr=[]
def gethash
h[1]=0
return h
end
arr[0]=gethash
puts arr[0].each {|k,v| puts “key #{k} value #{v}”}

For the above i get error saying “Undifined local variable or method ‘h’
for main:Object(NameError)”

may i know reason for this error?

Hi –

On Sun, 18 Apr 2010, Simbolla S. wrote:

arr[0]=gethash
puts arr[0].each {|k,v| puts “key #{k} value #{v}”}

For the above i get error saying “Undifined local variable or method ‘h’
for main:Object(NameError)”

may i know reason for this error?

The def keyword starts a new local scope. The same happens with class:

a = 1
class C
puts a # new local scope, so a is not defined
end

David


David A. Black, Senior Developer, Cyrus Innovation Inc.

THE Ruby training with Black/Brown/McAnally
COMPLEAT Coming to Chicago area, June 18-19, 2010!
RUBYIST http://www.compleatrubyist.com

On Sat, Apr 17, 2010 at 7:30 PM, Simbolla S. [email protected]
wrote:

arr[0]=gethash
puts arr[0].each {|k,v| puts “key #{k} value #{v}”}

to my dismay
def xxx… end
is not a closure
while
define_method :xxx is
IOW
h is just not visible in def while it would if you define gethas via
define_method

be careful though on the toplevel you cannot use define_method, do
something like
include( Module::new do
h = {}
define_method :xxx do h.tap{ |hh| h[1] = 0 } end
end )

puts xxx
xxx[:a] = 42
puts xxx

oh yes this code is ugly, but I wanted to demonstrate the semantics…
HTH
R.

On Apr 17, 11:30 am, Simbolla S. [email protected] wrote:

for main:Object(NameError)"
If you want h to be a global variable, accessible everywhere, prefix
it with a dollar sign:

$h={}
def foo
$h[1]=0
$h
end
foo
p $h
#=> {1=>0}

Gavin K. wrote:

On Apr 17, 11:30�am, Simbolla S. [email protected] wrote:

for main:Object(NameError)"
If you want h to be a global variable, accessible everywhere, prefix
it with a dollar sign:

$h={}
def foo
$h[1]=0
$h
end
foo
p $h
#=> {1=>0}

But usually it would be better instead to:

(1) pass h as an argument to method foo; or
(2) define a class with instance variable @h

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